class_docstr: Widget for proportionally dividing its internal area into a grid.
  
  This widget will automatically set the position and size of child widgets
  according to provided constraints.
  
  Parameters
  ----------
  spacing : int
      Spacing between widgets.
  **kwargs : dict
      Keyword arguments to pass to `Widget`.
code: def _add_total_width_constraints(solver, width_grid, _var_w):
      for ws in width_grid:
          width_expr = ws[0]
          for w in ws[1:]:
              width_expr += w
          solver.addConstraint(width_expr == _var_w)
  
imports: from __future__ import division
  import numpy
  from vispy.geometry import Rect
  from .widget import Widget
  from .viewbox import ViewBox
  from kiwisolver import Solver, Variable, UnsatisfiableConstraint
label_desc: Use image node_id 13 for calling the Grid obj's underlying member method code with example usage: obj._add_total_width_constraints(solver, width_grid, _var_w) without return types